Briquetted fuel and process of making



Patented May 12, 1936 UNITED STATES PATENT OFFICE BRIQUETTED FUEL AND PROCESS OF MAKING Frank Holz; Lillian, Ala, assignor of one-half t Cosmo Vacca, Bristol, Conn.

No Drawing. Application March 13, 1930, Serial N0. 435,644

10 Claims. (Cl. 44-15) an ever present problem toward the solution of which many suggestions .and many experiments have been made. These materials, although they are inherently valuable, frequently do not command a sufficient market in their comminuted form to make it worthwhile handling them, so that large amounts must be disposed of at some expense or allowed to accumulate in piles which are unsightly and frequently require land which would otherwise be of value for more useful purposes.

It is an object of my invention to convert such materials into valuable products at a cost much less than the increase in value and such that the resulting product would command a ready market in competition with other available fuel materials. To this end my invention comprises the cementing together of the comminuted materials by a carbonized organic material.

It has been suggested prior to my invention to mix such materials with organic matter such as tar, molasses and other organic materials and to carbonize the binder by a subsequent heat treatment. The suggestions, however, in the past have never proved successful largely because known briquettes have not held the material together with the tenacity necessary to produce a satisfactory commercial fuel. In other cases the suggested process has involved operations and materials either of kinds or in amounts which would be so expensive as to overcome any advantage from the use of cheap comminuted fuels.

I have now discovered that by the use of a sirup forming organic material, advantageously molasses or other saccharine sirup, a very small amount of the sirupy material will serve to cement a relatively large amount of comminuted fuel and when carbonized will hold the comminuted material so tenaciously together that the resulting material will compare favorably with the best coke or even with natural coal of graded size.

For some purposes, particularlyfor metallur gical use and in domestic stoves and furnaces the product of my invention is a product superior .to any which has been available before and consequently would serve not merely as a substitute but as an improved fuel commanding a higher price than natural fuels or coke.

My invention may be used to cement together 10 a large variety of comminuted fuels including coal dust, coke breeze, sawdust and many other materials. Nor is the invention'limited'to the use of strictly pulverized material but may serve, for

example, to cement materials as coarse as buck- 1| wheat or even pea coal.

The following example will illustrate the manner in which my invention may be used: 20 parts by weight of coal dust are thoroughly mixed with a saccharine solution comprising about 20 parts 20 by weight of water and about 1% parts by weight of heavy molasses. About 15 to 30 parts of water to one part of molasses may be used. These ingredients are thoroughly mixed until substantially all particles of the'coal are thoroughly 25 wet by the saccharine solution. The resulting mixture which will be about the consistency of a slush is then heated to the boiling point and cooked with constant or frequent stirring until the water is substantially all evaporated. Dur- 8. ing the cooking the white steam is given off from thematerial and when the steam ceases and begins to take on a bluish tinge the cooking is completed and the heating should be stopped. During the first part of the cooking a froth will 86 rise on the material. Later the bubbles will be larger and finally the material will take on the appearance of a volcano in which the bubbles coming through leave small shafts behind them. The cooking should be stopped as soon as this 40 final stage begins.

The material resulting from the cooking treatment is about the consistency of moist sand and may be compacted into molds either while hot or later after standing until cool. Advantageously the material is molded as soon as the cooln'ng treatment is complete and is carried to-the carbonizing stage without an intermediate cooling. The molding need not be done under pressure or with any elaborate precautions. It is merely necessary to compact the material sufiiciently so that the particles of the coal which have become covered with a film of the sirupy material are in contact with one another. The dropping of the material into open molds will ordinarily be 56 suflicient to effect this compacting. However, I prefer to use hinged ,molds which in closing serve to further compact the material and which, since they serve to cover the material and protect it from an oxidizing atmosphere, may be passed through the carbonizing furnace or oven without any special precautions to prevent their catching fire.

However, it is not necessary to effect the carbonizing treatment in molds, and if the oven is made air-tight, the material may be compacted and put onto a flat conveyor and thus passed through the ovenat a temperature which will carbonize the binder.

The carbonizing treatment may be effected either continuously or as a batch process; Advantageously it is performed as a continuous process by placing the molds on suitable cars or conveyors and passing them through a continuous oven or tunnel kiln such as is already commonly known in the baking and ceramic industries.

The temperature of the carbonizing treatment will depend upon the material being treated and upon the product which it is desired to produce. Thus, with coal dust from bituminous coal and molasses a temperature of 350 F. or even lower will serve to produce a high grade briquette which will burn with a luminous flame. Other temperatures may be used up to as high as 1200 to 1400 F. but in general I have found that temperatures between 650 and 700 F'. give most satisfactory results. When temperatures substantially higher than 700 are used the material should ordinarily be enclosed in molds which are fastened shut since otherwise the sudden release and expansion of gases resulting from the rapid carbonization and heating at such temperatures is likely to force the particles of the material away from each other and thus prevent them from becoming properly cemented during the carbonization treatment.

The duration of the heating obviously depends to a certain extent upon the temperature used. Thus, with lower temperatures a longer time of heating will be required for the thorough carbonization of the binder than when higher temperatures are used. When it is remembered that the primary purpose of the heat treatment is to carbonize the binder the best duration for any particular material and any particular temperature can be readily determined. A shorter time of heating will result in an inferior briquette which will not withstand weathering and rough treatment to the high degree which is possible by the use of my invention. A continued heating after the binder is satisfactorily carbonized will ordinarily not cause any substantial deterioration so far as the strength and resistance of the resulting briquette are concerned. In the case of fuels containing volatile matter, however, the continued heating will tend to drive ofi the volatile matter from the particles of the fuel.

The loss of volatiles during continued heating may be taken advantage of for the distillation of comminuted coal. Since the carbonized binder has already produced a strong porous material the volatile matter can readily escape from the particles of fuel without breaking up the material. Thus a high grade smokeless fuel may be produced from pulverized bituminous coal, lignite or even sawdust, the volatile matter which is driven of! may, of course, be recovered and the fuel gas and other by-products utilized in well known ways.

As is well known it is not every bituminous coal which can be used for the production of coke. On the contrary, only certain coals which fuse during the coking process can be satisfactorily used and these coals which are known as coking coals are in high demand, both because of the demand for gases and coal tar products and because of the need for coke as a smokeless fuel and in metallurgical processes. By the use of my invention it becomes possible to make a fuel which is more valuable as a smokeless fuel and also is more valuable for metallu gical uses. It is not necessary to use a coking coal for this process but any coal which contains volatile material may be comminuted and cemented into a porous mass by the process of my invention and then by a regulated heating treatment the volatile matter may be driven off through the porous structure, leaving a strong and resistant smokeless fuel.

For use in furnaces the fuel of my invention is particularly advantageous because it does not injure the grates or other furnace parts and similarly for metallurgical uses and particularly for forgings it is desirable because it does not form impurities in metal or scale on the forgings. The reason for these advantages in the resulting briquettes is not certainly understood but it seems likely that it is in part at least due to the fact that the pure carbon is more readily pulverized than are the impurities in the coal so that the coal dust which is thus treated produces a briquette of higher heating value and with substantially less impurities than the best coal or coke.

In case it is not desired to distill the volatile matter from the fuel such combustible gas and/or vapor as is released during the carbonization treatment may be burned in the oven or furnace itself tomaintain the carbonizing temperature.

Briquettes which are made from fuels containing volatile matter burn with a bright luminous flame but because of their porous structure may be more readily ignited than the coal from which they are made and if given an adequate supply of oxygen burn with a much hotter flame than ordinary coal. Such briquettes are particularly desirable for domestic use in open grates, etc.

Although I have described above a specific example in which I have set forth particular proportions of binder, water and comminuted fuel, it is to be understood that such proportions are only exemplary and may be varied in actual practice and often should be varied with different materials. The amount of the sirup-forming material should ordinarily be such as to form a thin coating over each particle of the fuel when mixed and cooked therewith as described above, but should be less than will fill the voids between the particles or make a coherent mass at this stage such as could be made into briquettes without carbonizing. Thus, for coarser fuel in which the surface is less a somewhat less amount of binder may be used than with finely divided fuel in which the surface area is relatively enormous. 0n the other hand, the amount of water used is not so much dependent upon the extent of surface as upon the nature of the surface and the volume of the voids. The dilution of the sirup-forming material must be such that it will be spread out over the entire surface of the fuel material and will wet substantially every particle thereof. Upon carbonization, this thin fllm of the sirup-forming material will be reduced even more in thickness by the loss of volatile materials, and, because of its thinness, will have little tendency to foam or hubble, but will form a relatively dense, strong bond between the particles of fuel.

Although I prefer to use molasses because it is a preeminently satisfactory material and one which is available in large quantities at low cost, nevertheless my invention is not limited to the use of molasses but other sirup-forming organic materials may be used and it is to be understood that they need, not be mixed with the fuel in a pure formj Thus, instead of a saccharine solution alone a refuse pulp of sugar beets which, as is well known contains a proportion of sugar which cannot be economically extracted, may be mixed with the comminuted fuel and the mixture cooked as already described, and carbonized. In the carbonization treatment the organic binder will be carbonized to form a tenacious bond and at the same time the cellulose of the beet pulp will also be largely carbonized thereby adding to the fuel value of the resulting product. Other vegetable pulps may be similarly used or sirupy waste liquors from various processes, and particularly from the boiling or steaming of wood, straw or other vegetable materials in the manufacture of pulp and paper may serve as the binder. These, however, I do not consider as advantageous as mo lasses. Nor is my invention limited to an aqueous syrup. The important criterion is that the syrup must be capable of dilution so"'as to coat each particle with a thin film and must be capable of carbonization to form a strong carbon bond between the contacting particles.

In any case, regardless of the particular binder used, it is important that it should be mixed with the comminuted fuel in a sumciently dilute form to thoroughly wet the fuel material and that it should thenbe cooked with agitation which will keep the binder evenly distributed over the fuel until it is substantially free from the diluent. It is also important to avoid carbonization or thermal decomposition of the binder at this stage. If the material is not sufiiciently cooked, the water remaining in the material will weaken the bond while it is being carbonized. If the material is not sufi'iciently agitated during the cooking so that the binder is not evenly distributed, some parts of the fuel will not be satisfactorily held together while in other parts an unnecessary amount of binder will be deposited and may even cause difiiculty by blocking the escape of gases from the interior of the briquette during the carbonization. If, on the other hand, the binder is substantially decomposed in the cooking treatment the particles will not be satisfactorily cemented together when the carbonization begins and as a result the product will be weakly held together if at all.

Although I have described the material when first mixed as being in the form of a slush it is to be understood that I do not limit this to any particular consistency. The consistency may vary from that of a mud to a thin slurry and I intend the word slush to include these various degrees. Obviously if larger particles are used such as pea coal, the consistency will be coarser, while if the fine dust is used the consistency would more nearly resemble that of a soft mud or a slurry.

Although I have referred to the product of my invention as "briquettes it is to be understood that I do not wish to limit it to any particular size or shape. I have found, however, that it is advantageous to treat the material in fairly small briquettes, that is, ones in which the minimum radius at any point within the briquette is about two inches or less. By minimum radius I mean the shortest distance from the point to any adjacent surface. 4

Some of the advantages of my invention may be attained even though the fuel is not to be' used in briquette form. Thus the distillation of the coal may with advantage be effected as described above even though the residue is not used in briquette form, and certain of the advantages and superior characteristics of the fuel briquetted according to my process above described may be attained by a similar treatment even though the fuel is not utilized as such in the briquetted form.

Although I have described above various alternatives which may be used as well as the specific example, it is to be understood that these are only exemplary and that other changes may be made within the scope of my invention.

This application is a continuation in part of my prior application Serial No. 329,957, filed January 2, 1929, which application was abandoned after being replaced by the present application.

I claim:

1. The process of briquetting comminuted coal .or other carbonaceous material, which comprises mixing the comminuted carbonaceous material with a dilute aqueous solution of a sirup-forming organic material, cooking the mixture with agitation under conditions adapted to remove substantially all water from the solution and to leave a thin, sticky coating of the sirup-forming organic material over the particles of carbonaceous material, compacting the dehydrated mixture, and subjecting it to a heat treatment sufilcient to carbonize the sirup-forming organic material.

2. The process of briquetting comminuted coal or other carbonaceous material, which comprises mixing the comminuted carbonaceous material with a solution of a sirup-forming organic material containing enough of said sirup-forming material that, after evaporation of the sticky diluent therefrom coating will be left covering the surfaces of the particles of carbonaceous material and said solution being sufiiciently dilute to thoroughly wet said surfaces, treating the mixture so as to evaporate the solvent and leave a coating of the 'sirup-forming material over the surfaces of the carbonaceous particles, compacting the dehydrated mixture, and subjecting it to a heat treatment suflicient to carbonize the sirupforming organic material.

3. The process as defined in claim 2, in which the sirup-forming material is a saccharine material.

4. The process as defined in claim 2, in which the sirupforming material is molasses.

5. The process as defined in claim 2, in which the dilute solution is in amount approximately sufiicient to form a slush.

6. The process as defined in claim 2, in which the carbonaceous material is pulverized and the solution with which it is mixed contains about one part of molasses in 15 to 30 parts of water and is used in amount sufiicient to thoroughly wet the surfaces of the particles of the carbonaceous material.

7. The method of cementing comminuted material to form a carbonaceous mass, which comprises mixing the comminuted solid fuel material with a solution of sirup-forming organic material, cooking and agitating the mixture at a temperature above the boiling point of the solution, cooling the mixture when substantially all the solvent has been evaporated and before destructive distillation of the sirup-forming material begins, compacting the mixture, and thereafter subjecting the mixture to a heat treatment adapted to carbonize the sirup-forming material.

8. The method as defined in claim 7, in which 7 the comminuted material contains decomposable organic matter and the evaporated mixture is subjected first to a preliminary heat treatment to carbonize the sirup-forming material, and then to a heat treatment adapted to carbonize organic material contained in the comminuted material.

9. The method of cementing comminuted material to form a carbonaceous mass, which comprises mixing the comminuted solid fuel material with a solution of shun-forming organic material, evaporating the solvent from 'said solution, and agitating the mixture at a temperature below that at which said organic material decomposes, and after substantially all of the solvent has been evaporated, and before destructive distillation or the sirup-iormlng material, compacting the mixture, and thereafter subjecting the mixture to a heat treatment adapted to carbonize the sirup-torming material.

10. A carbonaceous mass which comprises comminuted solid fuel material cemented together'by mixing the same with a dilute solution of simpforming organic material, evaporating the solvent trom said solution and'agitating the mixture at atemperature below that at which the organic material decomposes, compacting the mixture after substantially all of the solvent has been evaporated, but before destructive distillation or the sirup-forming material, compacting the mixture, and thereafter subjecting the mixture to a heat treatment adapted to carbonize the sirup-forming material.

FRANK HOLZ.

CERTIFICATE OF CORRECTION.

Patent N0. 2,040,609. May 12, 1936.

FRANK HOLZ.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, second column, line 40, claim 2, strike out the word "sticky"; and line 41, same claim, after "therefrom" insert the words a sticky; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day' of September, A. D. 1936.

' Henry Van Arsdale (Seal) Acting Commis:.ioner of Patents. 

